Exodus 12:16 - Ellicott's Commentary On The Whole Bible

In the first day there shall be an holy convocation. — The Passover was to be kept on the fourteenth day of Abib, at even. The seven following days were to be “days of unleavened bread.” On the first of these, the fifteenth of Abib (Leviticus 23:6), there was to be a “holy convocation,” i.e., a general gathering of the people to the door of the sanctuary for sacrifice, worship, and perhaps instruction. (Comp. Nehemiah 8:1.) The term “convocation” implies that the people were summoned to attend; and the actual summons appears to have been made by the blowing of the silver trumpets (Numbers 10:2). On the seventh day, the twenty-first of Abib, was to be another similar meeting. “No manner of work” was to be done on either of these two days; or rather, as explained in Leviticus 23:7-8, “no servile work.”